drtools规则使用快速入门之一

矫情吗；* 2022-07-21 11:26 257阅读 0赞

# 1、前言 #

Drools（JBoss Rules ）具有一个易于访问企业策略、易于调整以及易于管理的开源业务[规则引擎][Link 1]，符合业内标准，速度快、效率高。本文一个简单的例子讲解从java规则转化为规则引擎调用。

# 2、drtools规则 #

![20160715084943737][]

**rule**：定义一个规则。rule "ruleName"。一个规则可以包含三个部分：

属性部分：定义当前规则执行的一些属性等，比如是否可被重复执行、过期时间、生效时间等。

条件部分，即LHS，定义当前规则的条件，如  when Message(); 判断当前workingMemory中是否存在Message对象。

结果部分，即RHS，这里可以写普通java代码，即当前规则条件满足后执行的操作，可以直接调用Fact对象的方法来操作应用。

规则事例：

详细文法见：http://www.360doc.com/content/07/0705/18/7147\_596025.shtml

# 3、使用例子 #

## 3.1需要转化的java代码 ##

public int statusProcess(int faceStatus, double faceProbability, int tuStatus, double tuProbability) {
            if (faceStatus == 0 || tuStatus == 0) {
                return 0;
            }
    
    
            if (faceStatus == 1 || tuStatus == 1) {
                return 0;
            }
    
    
            if (faceStatus == 2 && tuStatus == 2) {
                double probability = tuProbability + faceProbability;
    
    
                if (probability>0.85 && tuProbability >= 0.85) {
                    return 1;
                } else if (tuProbability > 0.4 && tuProbability < 0.85 && probability >= 1.3) {
                    return 1;
                } else if (probability >= 0.8 && probability < 1.3) {
                    return 2;
                } else if (probability < 0.8) {
                    return 0;
                }
            }
    
    
            return 2;
        }

## 3.2 对应的规则文件 ##

package com.feinno.drools
    import com.feinno.drools.HelloWorldExample.ResultRate;
    
    
    rule "1"
        dialect "mvel"
    when
       m : ResultRate((faceStatus == -1 && tuStatus== -1 && status == -1 ), resultStatus : resultStatus )
    then
    	System.out.println( resultStatus ); 
         modify ( m ) {
    	      status = 1,
    	      resultStatus = 0
          };
    end
    
    rule "2"
        dialect "mvel"
    when
       m : ResultRate((faceStatus == 0 && tuStatus== 0 && status == -1 ), resultStatus : resultStatus )
    then
    	System.out.println( resultStatus ); 
         modify ( m ) {
    	      status = 1,
    	      resultStatus = 0
          };
    end
    
    rule "3"
        dialect "mvel"
    when
       m : ResultRate((faceStatus == 2 && tuStatus== 2&&tuProbability >= 0.85 && status == -1 ), resultStatus : resultStatus )
    then
    	System.out.println( resultStatus ); 
         modify ( m ) {
          status = 1,
          resultStatus =1
          };
    end
    
    
    
    rule "4"
        dialect "mvel"
    when
       m : ResultRate((faceStatus == 2 && tuStatus== 2&& tuProbability > 0.4 && tuProbability < 0.85 && probability>= 1.3 && status == -1 ), resultStatus : resultStatus )
    then
    	System.out.println( resultStatus ); 
         modify ( m ) {
          status = 1,
          resultStatus =1
          };
    end
    
    rule "5"
        dialect "mvel"
    when
       m : ResultRate((faceStatus == 2 && tuStatus== 2&& probability>= 0.8 && probability< 1.3 && status == -1 ), resultStatus : resultStatus )
    then
    	System.out.println( resultStatus ); 
         modify ( m ) {
          	status = 9,
          	resultStatus = 2
          };
    end
    
    rule "51"
        dialect "mvel"
    when
       m : ResultRate((faceStatus == 2 && tuStatus== 2&&tuProbability >= 0.85&& status == 9 ), resultStatus : resultStatus )
    then
    	System.out.println( resultStatus ); 
         modify ( m ) {
          status = 1,
          resultStatus = 1
          };
    end
    
    rule "6"
        dialect "mvel"
    when
       m : ResultRate((faceStatus == 2 && tuStatus== 2&& probability< 0.8 && status == -1 ), resultStatus : resultStatus )
    then
    	System.out.println( resultStatus ); 
         modify ( m ) {
          	status = 1,
          	resultStatus = 0
          };
    end

注意：

1、规则不能嵌套

2、规则不支持a+b，增加一个中间变量probability

## 3.3 对应的java对象 ##

public static class ResultRate{
    		int faceStatus;
    		double faceProbability;
    		int tuStatus;
    		double tuProbability;
    		int status;
    		int resultStatus;
    		double probability;
    		
    		public ResultRate(){
    			status = -1;
    		}
    		
    		public int getFaceStatus() {
    			return faceStatus;
    		}
    		public void setFaceStatus(int faceStatus) {
    			this.faceStatus = faceStatus;
    		}
    		public double getFaceProbability() {
    			return faceProbability;
    		}
    		public void setFaceProbability(double faceProbability) {
    			this.faceProbability = faceProbability;
    		}
    		public int getTuStatus() {
    			return tuStatus;
    		}
    		public void setTuStatus(int tuStatus) {
    			this.tuStatus = tuStatus;
    		}
    		public double getTuProbability() {
    			return tuProbability;
    		}
    		public void setTuProbability(double tuProbability) {
    			this.tuProbability = tuProbability;
    		}
    		public int getStatus() {
    			return status;
    		}
    		public void setStatus(int status) {
    			this.status = status;
    		}
    		public int getResultStatus() {
    			return resultStatus;
    		}
    		public void setResultStatus(int resultStatus) {
    			this.resultStatus = resultStatus;
    		}
    		
    		public double getProbability() {
    			return probability;
    		}
    
    		public void setProbability(double probability) {
    			this.probability = probability;
    		}
    
    		public void computeProbability(){
    			probability = faceProbability+tuProbability;
    		}
    		
    	}

##  3.4 测试程序 ##

public static void testRate()throws Exception {
    		String filepath = "C:\\目标路径\\ResultRate.drl";
    		final Reader source = new FileReader(filepath);
    		final PackageBuilder builder = new PackageBuilder();
    
    		//新建规则
    		builder.addPackageFromDrl(source);
    		if (builder.hasErrors()) {
    			System.out.println(builder.getErrors().toString());
    			throw new RuntimeException("Unable to compile ResultRate.drl");
    		}
    
    		// get the compiled package (which is serializable)
    		final Package pkg = builder.getPackage();
    		// add the package to a rulebase (deploy the rule package).
    		final RuleBase ruleBase = RuleBaseFactory.newRuleBase();
    		ruleBase.addPackage(pkg);
    		final StatefulSession session = ruleBase.newStatefulSession();
    		session.addEventListener(new DebugAgendaEventListener());
    		session.addEventListener(new DebugWorkingMemoryEventListener());
    		
    		//测试
    		ResultRate rusultRate = new ResultRate();
    		rusultRate.setFaceStatus(2);
    		rusultRate.setFaceProbability(0.3);
    		rusultRate.setTuStatus(2);
    		rusultRate.setTuProbability(0.90);
    		rusultRate.computeProbability();
    		
    		session.insert(rusultRate);
    		session.fireAllRules();
    		System.out.println("======================================");
    		
    		//规则库后测试
    		Package[] packs = ruleBase.getPackages();
    		for(int i = 0;i<packs.length;i++){
    			System.out.println(packs[i].getName());
    			ruleBase.removePackage(packs[i].getName());
    		}
    		ResultRate rusultRate2 = new ResultRate();
    		rusultRate2.setFaceStatus(2);
    		rusultRate2.setFaceProbability(0.3);
    		rusultRate2.setTuStatus(2);
    		rusultRate2.setTuProbability(0.90);
    		rusultRate2.computeProbability();
    		
    		System.out.println(rusultRate2.getResultStatus());
    		
    		//消除相关的处理
    		session.dispose();
    	}

# 4、参考文档 #

http://blog.csdn.net/kevin\_darkelf/article/details/50728137

http://www.360doc.com/content/07/0705/18/7147\_596025.shtml

[Link 1]: http://baike.baidu.com/view/1636209.htm
[20160715084943737]: /images/20220720/d2e78da31d4f4514a1473d1ddad917b5.png